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RE: Input sought on datatyping tradeoff

From: Manos Batsis <m.batsis@bsnet.gr>
Date: Fri, 12 Jul 2002 10:19:19 +0300
Message-ID: <E657D8576967CF448D6AF22CB42DD26908BFB2@ermhs.Athens.BrokerSystems.gr>
To: <www-rdf-comments@w3.org>


> -----Original Message-----
> From: Brian McBride [mailto:bwm@hplb.hpl.hp.com] 

>    <Jenny> <age>          _:a .
>    _:a     <xsdr:decimal> "10" .
> 
> This can be written in RDF/XML like this.
> 
>    <rdf:Description rdf:about="Jenny">
>      <foo:age xsdr:decimal="10"/>
>    </rdf:Description>

 
> SOME TEST CASES
> ===============
> 
> It is here that we need some advice, because we have a choice 
> to make in 
> the way we define the formal semantics.
> 
> A few simple test cases:
> 
> Test A:
> 
>    <Jenny> <ageInYears> "10" .
>    <John>  <ageInYears> "10" .
> 
> Should an RDF processor conclude that the value of the ageInYears 
> properties for Jenny and John are the same?

I guess so; The object is the same literal for both Jenny and John.



> There are variations on this test which should be considered 
> before answering.
> 
> Test A2:
> 
>    <Jenny> <ageInYears> "10" .
>    <Jenny> <testScore>  "10" .
> 
> Should an RDF processor conclude that the value of Jenny's ageInYears 
> property is the same as the value of Jenny's testScore property?

Same as above.


> Test A3:
> 
>    <Jenny> <ageInYears>   "10" .
>    <Film>  <title>        "10" .
> 
> Should an RDF processor conclude that the value of Jenny's 
> age property is 
> the same as the value of the Film's title property?  If the value the 
> <ageInYears> property is an integer, and the value of the 
> <title> property 
> is a string, they are not the same thing and are thus not equal.

Same as above. You have not given a type for the literal value.


> Now for a different kind of test.  How do the values of the 
> two idioms relate?
> 
> Test D:
> 
>    <Jenny>      <ageInYears> "10" .
>    <ageInYears> rdfs:range xsd:decimal .
> 
>    <John>  <ageInYears>   _:a .
>    _:a     xsdr:decimal   "10" .

> Should an RDF processor conclude that Jenny and John have the same 
> age?  [Note: in this example the range constraint is expressed using 
> rdfs:range.  We may have to introduce a special datatyping 
> range property, 
> but that is an independent detail for now.]

I don't like the result graph from the above. 


 
> It is not possible to have the answers to Tests A and Test D both be 
> yes.  Either the A's can be yes or D can be yes, but not 
> both.  We have to 
> decide which of these is the most important to have.

Why the use of literals? Why not a URI? The XSD spec at [1] give
http://www.w3.org/2001/XMLSchema-datatypes as the base datatype URI that
should be used by specs other than itself. I'd love to see the above
examples simply use that and append the literal value.



> CONCLUSION
> ==========
> 
> To end then, please send a message to www-rdf-comments@w3.org 
> (by 26 July 
> 2002) indicating whether you believe its more important to 
> have the answer 
> to test cases A be yes, or test case D be yes:
> 
>    Test A:
> 
>    <Jenny> <ageInYears> "10" .
>    <John>  <ageInYears> "10" .
> 
> Test D:
> 
>    <Jenny>      <ageInYears> "10" .
>    <ageInYears> <rdfs:range> <xsdr:decimal> .
> 
>    <John>  <ageInYears>      _:a .
>    _:a     <xsdr:decimal>   "10" .
> 
> 
> We would also like to know the reasons for this preference.

In that case, I'd vote for D as yes, since it involves some form of
explicit typing that an RDF processor should be aware of. A can be false
to the RDF processor but this will be of limited impact for most since
literal values will be essentially handled by an external application
anyway.

Manos
Received on Friday, 12 July 2002 03:18:58 GMT

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